The present invention relates generally to new and novel improvements in the printing of scannable bar codes which appear visibly red. More particularly, the present invention relates to printing ribbons capable of printing bar codes which appear visibly red and which are scannable by conventional bar code scanning systems utilizing lasers emitting light having wavelengths in the visible red region and collectors which collect the light reflected from the bar codes.
The identification of products with bar codes is a common practice in retail stores and other similar applications to assist in such activities as the pricing of merchandise, the checkout of customers, and the control and identification of inventory. One widely used product identification bar code convention is the uniform product code (UPC) which consists of alternating dark and light vertical bands of varying-widths. The uniform product code (UPC) has become widely accepted as the standard bar coding method in the retail product area.
A conventional uniform product code (UPC) consists of a series of dark vertical bands of varying widths separated by a series of light vertical bands also of varying widths. When printed on a substrate such as white paper or a printing medium having a light color, the uniform product code (UPC) typically consists of a series of printed vertical black bands of varying widths separated by sufficient spacing to allow the light vertical bands to be formed by the white or light color of the paper or other printing medium remaining between the printed vertical black bands. In other cases, such as when a uniform product code (UPC) is printed on a substrate having a metallic surface or on other materials having a dark color, both the black vertical bands as well as the white vertical bands are printed.
While the convention has been to use black vertical bands separated by white vertical bands for a uniform product code (UPC), it is sometimes desirable to enhance the visual appeal of the uniform product code (UPC) by utilizing other colors. The use of other colors is generally acceptable as long as the contrast between the dark vertical lines and the light vertical lines is sufficient to allow conventional bar code scanners to read the uniform product code (UPC). However, the bar code scanners in many conventional bar code scanning systems use lasers, such as helium neon lasers, which emit light having wavelengths in the visible red region, and collectors which collect the light reflected from the bar codes. When this is the case, a uniform product code (UPC) utilizing the color red for the dark vertical bands would reflect a significant portion of the light emitted from a laser emitting light having wavelengths in the visible red region. Consequently, the red vertical bands appear "light" to the collector which collects the light reflected from the bar code. Thus, in the past, it has been thought that the color red could not be used for the dark vertical bands of bar codes because the bar codes could not be read by conventional bar code scanning systems utilizing lasers emitting light having wavelengths in the visible red region and collectors which collect the light reflected from the bar codes.
Accordingly, an object of the present invention is the provision of a printing ribbon for printing bar codes which appear visibly red and which are scannable by conventional bar code scanning systems utilizing lasers emitting light having wavelengths in the visible red region and collectors which collect the light reflected from the bar codes.
Another object of the present invention is to provide a printing ribbon for printing uniform product codes (UPC) on products which appear visibly red and which are scannable by conventional bar code scanning systems utilizing lasers emitting light having wavelengths in the visible red region and collectors which collect the light reflected from the bar codes.
These and other objects of the present invention are attained by the provision of a printing ribbon for printing bar codes which appear visibly red and which are scannable by conventional bar code scanning systems utilizing lasers emitting light having wavelengths in the visible red region and collectors which collect the light reflected from the bar codes. This is accomplished by the provision of a printing ribbon having a printing medium adhered to a backing element. The printing medium preferably includes an interspersed distribution of pigments in a binding substrate. These pigments can include a combination of red coloring agents, such as visible red pigments which appear visibly red under broad spectrum light, fluorescent pigments which are inactive under light having wavelengths in the visible red region, but which are activated by broad spectrum light, and red absorbing agents, such as visible black or other colored pigments. The fluorescent pigments are activated under broad spectrum light and partially mask or shield the dark color of the visible black or other colored pigments, thus making the printed image appear red in broad spectrum light. This results in printed bar codes which visually appear red under broad spectrum light, yet are scannable by bar code scanning systems utilizing lasers emitting light having wavelengths in the visible red region and collectors which collect the light reflected from the bar codes.
Other objects, advantages and novel features of the present invention will become apparent in the following detailed description of the invention when considered in conjunction with the accompanying drawings.